Example code showing how to use a Kafka Spout in Storm 0.9.3
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README.md
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README.md

Overview

This is an example repo that shows how to set up a Java project to use the KafkaSpout that is now part of Storm with version 0.9.3. Other examples online at the time of this writing are either wrong (outdated) or show how to run with KafkaSpout in local mode but not "cluster-mode" against a separate Kafka system or confusing in that they add a lot of superfluous stuff (and do the example in Scala). This example is in the vein of "do the simplest thing that can work".

Getting the pom set up right so that the incompatible logging libraries between Storm and Kafka don't shoot the topology in the head is the hardest part (lost a day of my life getting that sorted out). So that is probably the most fragile piece - it may break on other systems and with other versions (past or future).

The topologies are a basic wordcount topology, based on Chapter 1 of P. Taylor Goetz's Storm Blueprints book.

There are two versions:

  • one that uses a in-memory SentenceSpout (taken from the Storm Blueprints example)
  • one that uses a Kafka sentence Topic as the source of sentences

Each of those comes in two variants

  • one that does not anchor and ack tuples ("non-reliable")
  • one that anchors and acks tuples ("reliable")

Tested against

This code has been tested on Linux in cluster-mode using:

  • Storm 0.9.3
  • Kafka 2.10-0.8.1.1
  • the version of Zookeeper that comes with Kafka 2.10-0.8.1.1 (zookeeper-3.3.4)

and

  • Storm 0.9.3
  • Kafka 2.10-0.8.2-beta
  • the version of Zookeeper that comes with kafka_2.10-0.8.2-beta (zookeeper-3.4.6)

Usage

The in-memory SentenceSpout topologies can be run in local mode by setting the System property localmode=true (defaults to false).

The KafkaSpout based topologies cannot be run in local mode.

Running the KafkaSpout based wordcount example

Install and start ZooKeeper, Storm and Kafka (see version notes above). This example assumes all are running on localhost. If not, you will need to change the zkHostPort settings in the kafka WordCountAckedTopology and WordCountNonAckedTopology classes to point to where zookeeper is running.

Create the "sentences" topic in Kafka:

$KAFKA_BIN/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic sentences

The pom.xml can be adjusted to specify which version of Kafka you want to depend on. The default is 2.10-0.8.2-beta.

Compile and build the uber-jar:

mvn clean package

Submit the uber-jar to storm and specify either the Acked or NonAcked Topology:

storm jar target/kstorm-1.0-SNAPSHOT-jar-with-dependencies.jar quux00.wordcount.kafka.WordCountNonAckedTopology
# or
storm jar target/kstorm-1.0-SNAPSHOT-jar-with-dependencies.jar quux00.wordcount.kafka.WordCountAckedTopology

Now you'll need to put some sentences into the sentence topic.

You can either do it manually with:

$KAFKA_BIN/kafka-console-producer.sh --broker-list localhost:9092 --topic sentences
(and now type a bunch of sentences in)

or use the example code I provide that puts in a bunch of sentences over a few minutes.

java -cp target/kstorm-1.0-SNAPSHOT-jar-with-dependencies.jar quux00.wordcount.kafka.PopulateKafkaSentenceTopic

If you have the Storm UI launched (storm ui) you can go to http://localhost:8080 and watch the progress of the topology